Created gltools and glstereo from gldemo

-major restructure of gldemo
-added gltools: contains general-use GL code
-added glstereo: supports stereo+distort render
-reformatted to conform to the rest of libnsb_ovr
Skysphere and commandline options for gldemo

-added skysphere rendering and some shaders
-command-line options (eg. --rift)
-animation uses GLUT_ELAPSED_TIME now
Update Makefile.am to properly build gldemo